Variation of the resolving power of a mass spectrometer with pressure

Abstract

The variation of the resolving power of a mass spectrometer with the variation of pressure within the analyzer tube has been studied using the singly and doubly charged inert gas ions Ne +, A + and A 2+. The resolving powers were found to decrease approximately exponentially in the pressure range studied, i.e. from 6 · 10 −5 to 6 · 10 −4 torr. The rate of fall of the resolving power with increase of pressure is more pronounced in the case of higher mass. A comparative study of the effect was made in the case of singly and doubly charged ions (Ne + and A 2+) of the same mje ratio. An attempt has been made to explain theoretically the effect mentioned above, assuming energy broadening of the ion beam due to elastic scattering and resonance charge exchange processes. The effect of angular broadening due to elastic scattering of the ion beam has also been considered.